Exposure to toxic agents, such as CW agents and related toxins, is a potential hazard to the armed forces and to civilian populations, since CW agents are stockpiled by several nations, and other nations and groups actively seek to acquire these materials. Some commonly known CW agents are bis-(2-chloroethyl) sulfide (HD or mustard gas), pinacolyl methylphosphonothiolate (soman or GD), sarin (GB), cyclosarin (GF), and 0-ethyl S-(2-diisopropylamino)ethyl methylphosphonothiolate (VX), as well as analogs and derivatives of these agents. These CW agents are generally delivered as fine aerosol mists which, aside from presenting an inhalation threat, will deposit on surfaces of military equipment and hardware, including uniforms, weapons, vehicles, vans and shelters. Once such equipment and hardware is contaminated with one or more of such highly toxic agents, the agent must be removed in order to minimize contact hazards and to return the item to service.
For this reason, there is an acute need to develop and improve technology for decontaminating surfaces contaminated with highly toxic materials, such as CW agents. This is especially true for the class of toxic chemicals known as nerve agents, which are produced and stockpiled for both industrial use and as CW agents. One class of nerve agent with a high level of potential lethality is the class that includes organophosphorus-based (“OP”) compounds, such as sarin, soman, and VX. Such agents can be absorbed through inhalation and/or through the skin of an animal or person. The organophosphorus-type (“OP”) CW materials typically manifest their lethal effects against animals and people by inhibiting acetylcholine esterase (“AChE”) enzyme at neuromuscular junctions between nerve endings and muscle tissue to produce an excessive buildup of the neurotransmitter acetylcholine, in an animal or person. This can result in paralysis and death in a short time.
In addition to the concerns about CW agents, there is also a growing need for decontaminating surfaces contaminated with toxic industrial chemicals that include, for example, insecticides and their corresponding intermediates and precursors. Examples of toxic industrial chemicals include AChE-inhibiting pesticides such as parathion, paraoxon, diazinon and malathion. Said compounds are manufactured on the industrial scale and, in the event of a leak or dispersal, can result in contamination of large areas that must be effectively decontaminated in order to control the spread of toxins as well as limit/minimize threat to personnel in said areas. Thus, it is very important to be able to effectively decontaminate surfaces with a broad spectrum of toxic chemicals, including, but not limited to, organophosphorus-type compounds.
Furthermore, CW agents and related toxins are so hazardous that simulants have been developed for purposes of screening decontamination and control methods. These simulants include 2-chloroethylphenyl sulfide (CEPS) and 2-chloroethylethyl sulfide (CEES), an HD simulant, dimethyl methyl phosphonate (DMMP), a G-agent simulant, and O-ethyl-S-ethyl phenylphosphonothioate (DPPT), a VX simulant.
Up until about the year 2000, the U.S. Army used a decontamination solution called DS2, which is composed (by weight) of 2% NaOH, 28% ethylene glycol monomethyl ether, and 70% diethylenetriamine (Richardson, G. A. “Development of a package decontamination system,” EACR-1 310-17, U.S. Army Edgewood Arsenal Contract Report (1972)). This solution was used to decontaminate surfaces contaminated with CW agents. Although this decontamination solution is effective against CW agents, DS2 is quite toxic, flammable, highly corrosive, and releases toxic by-products into the environment. In addition, manufacture of DS2 exposes personnel to undue risks due to the toxic nature of the ingredients. For example, a component of DS2, namely diethylenetriamine, is a teratogen, so that the manufacture and use of DS2 also presents a potential health risk. DS2 protocol calls for waiting 30 minutes after DS2 application, then rinsing the treated area with water in order to complete the decontamination operation. The long mission time and need for water wash can present logistical implications, especially in battlefield environments.
The U.S. Army previously developed and employed a solid decontamination material called XE555 resin (Ambergard™ Rohm & Haas Company, Philadelphia, Pa.) to remove toxic agents from the contaminated surface. The resin powder was applied to the surface using a mitt. XE555 has several disadvantages, however. Although effective at removing chemical agents, XE555 does not possesses sufficient reactive properties to neutralize the toxic agent(s) picked-tip (absorbed) by this resin. Thus, after use for decontamination purposes, XE555 itself presents an ongoing threat from off-gassing toxins and/or vapors mixed with the resin. Further, XE555 resin presents a contact and inhalation hazard. XE555 is expensive to manufacture in the quantities required for decontamination purposes. As a result, XE555 resin was not suitable for large area decontamination operations.
Reactive sorbents have been developed and used to both absorb and react with highly toxic materials to yield less toxic products (U.S. Pat. No. 6,852,903). One example is M100 Sorbent Decontamination System (SDS) for decontaminating highly toxic materials. The M100 SDS utilizes an aluminum oxide-based reactive sorbent called A-200-SiC-1005S, which is in the form of a powder. A-200-SiC-1005S is made from a dehydroxylated silica-alumina powder blended with 5% carbon to achieve a grey color. The reactive sorbent powder acts as an inexpensive, non-corrosive, non-harmful absorber designed to be rubbed onto a contaminated surface. The decontamination powder does not require water rinse or special disposal. The reactive sorbent is structured to flow readily across a contaminated surface, and is highly porous allowing it to rapidly absorb the highly toxic material from the contaminated surface. The absorbed highly toxic material is strongly retained within the pores of the reactive sorbent, which reacts to form less toxic products thereby minimizing off-gassing and contact hazards.
Another example is found in U.S. Pat. No. 5,689,038, to Bartram and Wagner, disclosing the use of an aluminum oxide, or a mixture of aluminum oxide and magnesium monoperoxyphthalate (MMPP), as reactive sorbents to decontaminate surfaces contacted with droplets of chemical warfare agents. It has been reported that both materials were able to effectively remove such toxic agents from a surface to the same extent as XE555. In addition, both materials represented improvements in chemical warfare agent degrading reactivity and in reducing off-gassing of toxins relative to XE555. The reported sorbents were based on pre-existing, commercially available materials, such as Selexsorb CD™, a product of the Alcoa Company. Essentially, Bartram and Wagner reported that their aluminum oxide is modified by size reduction, grinding or milling.
Another example is U.S. Pat. No. 6,537,382 to Bartram and Wagner, disclosing the use of two types of reactive sorbents. One comprises metal exchanged zeolites such as silver-exchanged zeolite, and the other comprises sodium zeolites. The reactive sorbents remove, and then decompose chemical agents from the surface being decontaminated. Similar in all reactive sorbents, this dual action provides the advantage of reducing the risks associated with potential offgassing from the sorbent, and reducing the toxicity of the sorbent for disposal purposes.
In still another example, U.S. Pat. No. 8,530,719 to Peterson et al. disclose the use of zirconium hydroxide as a base for a solid phase decontamination media. The authors report the ability of zirconium hydroxide, and zirconium hydroxide loaded with zinc, triethylenediamine, or zinc plus triethylenediamine to detoxify chemical agents VX and GD. No data regarding the ability of these media to decontaminate a surface contaminated with toxic chemicals is reported.
Detoxification of surfaces in a field setting is essential to improving user safety as well as reducing the time necessary for contaminated equipment to return to service. As such new agents and methods of detoxification are needed.